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Straight line mechanism

About: Straight line mechanism is a(n) research topic. Over the lifetime, 36 publication(s) have been published within this topic receiving 175 citation(s).

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Journal ArticleDOI
01 Dec 1985
TL;DR: A hexapod walking machine using an approximate straight line mechanism was developed and several basic experiments were performed to demonstrate the properties of this type of walking machine.
Abstract: Legged locomotion over irregular terrain is composed of body-propelling motion and terrain-adapting motion. Although conventional walking machines with three degrees-of-freedom for each leg can adapt their feet on irregular ground using flexible leg freedom, such machines generally require a tremendously complex control scheme for the body-propelling motion. A walking machine with decoupled freedoms is based on the idea that body-propelling motion is realized by only one degree-of-freedom, and this freedom can be perfectly decoupled from the freedoms for terrain adaptability. As an application of such a walking machine, a hexapod walking machine using an approximate straight line mechanism was developed and several basic experiments were performed to demonstrate the properties of this type of walking machine.

41 citations

Proceedings ArticleDOI
17 Aug 2014
Abstract: Many robotic joints powered by linear actuators suffer from a loss of torque towards the limits of the range of motion. This paper presents the design of a fully backdriveable, force controllable rotary actuator package employed on the Tactical Hazardous Operations Robot (THOR). The assembly pairs a ball screw-driven linear Series Elastic Actuator (SEA) with a planar straight line mechanism. The mechanism is a novel inversion of a Hoeken’s four-bar linkage, using the ball screw as a linear input to actuate the rotary joint. Link length ratios of the straight line mechanism have been chosen to optimize constant angular velocity, resulting in a nearly constant mechanical advantage and peak torque of 115 [Nm] throughout the 150° range of motion. Robust force control is accomplished through means of a lookup table, which is accurate to within ±0.62% of the nominal torque profile for any load case.Copyright © 2014 by ASME

18 citations

Journal ArticleDOI
Abstract: Straight-line compliant mechanisms are important building blocks to design a linear-motion stage, which is very useful in precision applications. However, only a few configurations of straight-line compliant mechanisms are applicable. To construct more kinds of them, an approach to design large-displacement straight-line flexural mechanisms with rotational flexural joints is proposed, which is based on a viewpoint that the straight-line motion is regarded as a compromise of rigid and compliant parasitic motion of a rotational flexural joint. An analytical design method based on the Taylor series expansion is proposed to quickly obtain an approximate solution. To illustrate and verify the proposed method, two kinds of flexural joints, cross-axis hinge and leaf-type isosceles-trapezoidal flexural(LITF) pivot are used to reconstruct straight-line flexural mechanisms. Their performances are obtained by analytic and FEA method respectively. The comparisons of the results show the accuracy of the approach. Both examples show that the proposed approach can convert a large-deflection flexural joint into approximate straight-line mechanism with a high linearity that is higher than 5 000 within 5 mm displacement. This can lead to a new way to design, analyze or optimize straight-line flexure mechanisms.

14 citations

Journal ArticleDOI
Abstract: Very few kinematicians are aware of the existence of the focal linkage, which is an overconstrained one. Since there are many applications that could be derived from the linkage or from its derivatives, a thorough investigation has been made into the properties of the focal linkage. Here, a geometric approach as well as an algebraic one clears up some of the mystery that hangs around the mechanism. One of the main results that is achieved in the paper is the invention of a new eight-bar linkage containing a bar having rectilinear translation.

13 citations

05 Sep 1978
Abstract: Linkage mechanisms for industrial manipulators are disclosed which are based on so-called straight line mechanisms. The preferred straight line mechanism is of the conchoid type. The linkage mechanisms may be employed to move functional elements of industrial manipulators in straight lines without the use of lead screws or revolute jointed arms.

11 citations

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